In many fields it is important that images displayed on electronic displays appear the same over time and on different displays. For example, in radiology it is important that a displayed medical image appears having the same contrast from year-to-year as a disease is followed or as the image is viewed on different displays. Therefore, standards exist for the calibration of displays to ensure consistency of display between devices and consistency over time. Color standards are often reached through International Color Consortium (ICC) related correction and calibration tools. In radiology, one industry standard for grayscale display and calibration is in Digital Imaging and Communications in Medicine (DICOM) Part 14, the Gray Scale Display Function (GSDF), the content of which is incorporated herein by reference in its entirety.
It is common practice for medical device manufactures whose equipment contains or functions in association with a display system to offer GSDF or similar calibration as a product feature. This technology operates either as an integral unit to the device or as a third party add-on product. In the first case, a sensor within the display system monitors part or all of the luminance generated through the display's light path and supplies information to control components to correct or maintain the display response relevant to the GSDF. Medical physicists and other practitioners can monitor the changes in calibration requirements of various devices over time to ensure they are performing within limits and that the information displayed to physicians is displayed consistently.
Recently, there has been an increase in usage of client-server systems for the display of medical images. In this case, rather than images being generated on a designated medical device such as, for example, a PACS workstation or modality console with integral display components, the medical images are rendered on a central server and displayed on a client device which can be separated by a large distance from the server, and even outside the hospital where the server is deployed. Also, the client devices have evolved from closely controlled components of the medical device to commodity computers, laptops, tablet computers and even smart phones. The capacity of these devices to support internal or third party calibration varies widely.
While the designated medical devices have been used at fixed locations such as, for example, dark rooms or radiology reading rooms, the new devices are mobile and, therefore, introduce widely varying ambient light levels as a new variable to the calibration of image display. Mobile devices are used in widely varying situations such as, for example, offices, various other indoor locations (restaurants, theatres, residences) as well as outdoors, thus creating a wide range of possible lighting environments.
In addition to good manufacturing practice in industry, the application and routine maintenance of display quality assessments in the medical field can be a requirement for accreditation or reimbursement. With the adoption of mobile devices for these various color calibration or medical the Gray Scale Display Function (GSDF) consistency sensitive applications, the number of possible devices requiring monitoring may expand dramatically.